Along with the recent explosive increase of data capacities that business enterprises use, there are increasing demands for a more efficient system for storing and managing data. One method for solving this problem is the integration of storage devices (integration of internal storage devices in the whole enterprise and building a common storage infrastructure environment instead of constructing and maintaining storage systems for respective departments and operations).
Such integration enables highly efficient use of the storage devices, while cutting down and optimizing operation and maintenance costs. Such service is called a private cloud storage service, which is used within enterprises and affiliated business groups. Meter rate accounting based on the capacity of the storage areas of the storage system is applied to charge fees for the use of such storage services including the maintenance, operation and management of the storage system.
In contrast to the private cloud system, there is provided a conventional cloud system. According to the conventional cloud system, clients such as multiple private users and business users share and use storage sources and processing functions of information apparatuses constructed in data centers or the like through the internet. Also according to the conventional cloud system, meter rate accounting based for example on the capacity of the storage areas is applied to charge fees for such services. The arts disclosed in patent literatures 1 and 2 are examples related to such background art.
Patent literature 1 teaches a storage system in which memory devices of storage systems are divided into multiple tiers, wherein high speed devices are assigned to upper level tiers and low speed devices are assigned to lower level tiers, and an optimum tier is selected in response to the status of use of a data by the user so as to store the data in the selected tier. The literature teaches acquiring the time of use and the used capacity of the tier in which the data is stored in order to charge fees.
Further, patent literature 2 discloses a storage accounting system in which a storage service provider (SSP) providing operation and management service of storage devices has a plurality of storages which are divided into multiple sections and provided for service to multiple users, wherein the users pay charges for using the storage system. The accounting system ensures a minimum required data access rate for the user and changes the charged fees based on the demands of the users and the provided data access speed.